EP2258404B1

EP2258404B1 - Method of sterilizing using compositions containing fluorine substituted olefins

Info

Publication number: EP2258404B1
Application number: EP10011131.9A
Authority: EP
Inventors: Hang T. Pham; Rajiv R. Singh
Original assignee: Honeywell International Inc
Current assignee: Honeywell International Inc
Priority date: 2002-10-25
Filing date: 2003-10-27
Publication date: 2017-08-02
Anticipated expiration: 2023-10-27
Also published as: KR20120088873A; JP4699758B2; EP2277602A2; CN106085361A; TW200424305A; PT1563032E; ES2645635T3; JP2020015920A; JP2006512426A; TR201908011T4; WO2004037752A3; EP2228421B1; JP2013122056A; CN106753250A; CN106085362A; JP2021152177A; EP2277943A3; ES2321796T3; EP2277972A3; EP3170880B1

Abstract

A method of sterilizing an article comprises contacting said article with a composition comprising at least one fluoroalkene of Formula I: XCF z R 3-z (I) where X is a C 2 or a C 3 unsaturated, substituted or unsubstituted, alkyl radical, R is independently Cl, F, Br, I or H, and z is 1 to 3.

Description

FIELD OF THE INVENTION

This invention relates to compositions having utility in sterilization.

BACKGROUND OF THE INVENTION

Fluorocarbon based fluids have found widespread use in many commercial and industrial applications. For example, fluorocarbon based fluids are frequently used as a working fluid in systems such as air conditioning, heat pump and refrigeration applications. The vapor compression cycle is one of the most commonly used type methods to accomplish cooling or heating in a refrigeration system. The vapor compression cycle usually involves the phase change of the refrigerant from the liquid to the vapor phase through heat absorption at a relatively low pressure and then from the vapor to the liquid phase through heat removal at a relatively low pressure and temperature, compressing the vapor to a relatively elevated pressure, condensing the vapor to the liquid phase through heat removal at this relatively elevated pressure and temperature, and then reducing the pressure to start the cycle over again.
While the primary purpose of refrigeration is to remove heat from an object or other fluid at a relatively low temperature, the primary purpose of a heat pump is to add heat at a higher temperature relative to the environment.
Certain fluorocarbons have been a preferred component in many heat exchange fluids, such as refrigerants, for many years in many applications. For, example, fluoroalkanes, such as chlorofluoromethane and chlorofluoroethane derivatives, have gained widespread use as refrigerants in applications including air conditioning and heat pump applications owing to their unique combination of chemical and physical properties. Many of the refrigerants commonly utilized in vapor compression systems are either single components fluids or azeotropic mixtures.
Concern has increased in recent years about potential damage to the earth's atmosphere and climate, and certain chlorine-based compounds have been identified as particularly problematic in this regard. The use of chlorine-containing compositions (such as chlorofluorocarbons (CFC's), hydrochlorofluorocarbons (HCF's) and the like) as refrigerants in air-conditioning and refrigeration systems has become disfavored because of the ozone-depleting properties associated with many of such compounds. There has thus been an increasing need for new fluorocarbon and hydrofluorocarbon compounds and compositions that offer alternatives for refrigeration and heat pump applications. For example, it has become desirable to retrofit chlorine-containing refrigeration systems by replacing chlorine-containing refrigerants with non-chlorine-containing refrigerant compounds that will not deplete the ozone layer, such as hydrofluorocarbons (HFC's).
It is generally considered important, however, that any potential substitute refrigerant must also possess those properties present in many of the most widely used fluids, such as excellent heat transfer properties, chemical stability, low- or no-toxicity, non-flammability and lubricant compatibility, among others.
Applicants have come to appreciate that lubricant compatibility is of particular importance in many of applications. More particularly, it is highly desirably for refrigeration fluids to be compatible with the lubricant utilized in the compressor unit, used in most refrigeration systems. Unfortunately, many non-chlorine-containing refrigeration fluids, including HFC's, are relatively insoluble and/or immiscible in the types of lubricants used traditionally with CFC's and HFC's, including, for example, mineral oils, alkylbenzenes or poly(alpha-olefins). In order for a refrigeration fluid-lubricant combination to work at a desirable level of efficiently within a compression refrigeration, air-conditioning and/or heat pump system, the lubricant should be sufficiently soluble in the refrigeration liquid over a wide range of operating temperatures. Such solubility lowers the viscosity of the lubricant and allows it to flow more easily throughout the system. In the absence of such solubility, lubricants tend to become lodged in the coils of the evaporator of the refrigeration, air-conditioning or heat pump system, as well as other parts of the system, and thus reduce the system efficiency.
With regard to efficiency in use, it is important to note that a loss in refrigerant thermodynamic performance or energy efficiency may have secondary environmental impacts through increased fossil fuel usage arising from an increased demand for electrical energy.
Furthermore, it is generally considered desirably for CFC refrigerant substitutes to be effective without major engineering changes to conventional vapor compression technology currently used with CFC refrigerants.
Flammability is another important property for many applications. That is, it is considered either important or essential in many applications, including particularly in heat transfer applications, to use compositions which are non-flammable. Thus, it is frequently beneficial to use in such compositions compounds which are nonflammable. As used herein, the term "nonflammable" refers to compounds or compositions which are determined to be nonflammable as determined in accordance with ASTM standard E-681, dated 2002. Unfortunately, many HFC's which might otherwise be desirable for used in refrigerant compositions are not nonflammable. For example, the fluoroalkane difluoroethane (HFC-152a) and the fluoroalkene 1,1,1-trifluorpropene (HFO-1243zf) are each flammable and therefore not viable for use in many applications.
Higher fluoroalkenes, that is fluorine-substituted alkenes having at least five carbon atoms, have been suggested for use as refrigerants. U.S. Patent No. 4,788,352 - Smutny is directed to production of fluorinated C₅ to C₈ compounds having at least some degree of unsaturation. The Smutny patent identifies such higher olefins as being known to have utility as refrigerants, pesticides, dielectric fluids, heat transfer fluids, solvents, and intermediates in various chemical reactions. (See column 1, lines 11 - 22).
While the fluorinated olefins described in Smutny may have some level of effectiveness in heat transfer applications, it is believed that such compounds may also have certain disadvantages. For example, some of these compounds may tend to attack substrates, particularly general-purpose plastics such as acrylic resins and ABS resins. Furthermore, the higher olefinic compounds described in Smutny may also be undesirable in certain application because of the potential level of toxicity of such compounds which may arise as a result of pesticide activity noted in Smutny. Also, such compounds may have a boiling point which is too high to make them useful as a refrigerant in certain applications.
Bromofluoromethane and bromochlorofluoromethane derivatives, particularly bromotrifluoromethane (Halon 1301) and bromochlorodifluoromethane (Halon 1211) have gained widespread use as fire extinguishing agents in enclosed areas such as airplane cabins and computer rooms. However, the use of various halons is being phased out due to their high ozone depletion. Moreover, as halons are frequently used in areas where humans are present, suitable replacements must also be safe to humans at concentrations necessary to suppress or extinguish fire.
Applicants have thus come to appreciate a need for compositions, and particularly heat transfer compositions, fire extinguishing/suppression compositions, blowing agents, solvent compositions, and compatibilizing agents, that are potentially useful in numerous applications, including vapor compression heating and cooling systems and methods, while avoiding one or more of the disadvantages noted above.
US 6 300 378 relates to bromine-containing tropodegradable chemical additives to decrease the flammability of normally flammable refrigerants, foam blowing agents, cleaning solvents, aerosol propellants, and sterilants.
WO 02/072159 relates to a sterilization gas for use in sterilization equipment for such as medical instruments which is a replacement for ethylene oxide sterilants including dichlorodifluoromethane.
JP H04 110388 relates to a heat transfer medium comprising an organic compound which can be represented by the molecular formula C₃H_mF_n (where m is from 1 to 5, n is from 1 to 5 and m + n = 6) and which has one double bond in the molecular structure.

SUMMARY

Applicants have found that the above-noted need, and other needs, can be satisfied by a method of sterilizing an article comprising contacting said article with a composition comprising a pentafluoropropene (HFO-1225), and a sterilant composition comprising a pentafluoropropene (HFO-1225), preferably wherein the composition further comprises a chemical sterilant selected from the group consisting of ethylene oxide, formaldehyde, hydrogen peroxide, chlorine dioxide or ozone.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

THE COMPOSITIONS

The present invention is directed to compositions comprising a pentafluoropropene (HFO-1225). Fluoroalkene compounds are sometimes referred to herein for the purpose of convenience as hydrofluoro-olefins or "HFOs" if they contain at least one hydrogen Although it is contemplated that the HFOs of the president mentioned may contain two carbon - carbon double bonds, such compounds at the present time are not considered to be preferred.
The preferred compounds of the present invention, namely, HFO-1225 are known materials and are listed in Chemical Abstracts databases. HFO-1225 is commercially available, from example from Syntex Chemical Co. Furthermore, methods are described generally in the patent literature for producing fluoroalkenes. For example, the production of fluoropropenes such as CF₃CH=CH₂ by catalytic vapor phase fluorination of various saturated and unsaturated halogen-containing C₃ compounds is described in U.S. Patent Nos. 2,889,379 ; 4,798,818 and 4,465,786 ,. U.S. Patent No. 5,532,419 , , discloses a vapor phase catalytic process for the preparation of fluoroalkene using a chloro- or bromo-halofluorocarbon and HF. EP 974,571 discloses the preparation of 1,1,1,3-tetrafluoropropene by contacting 1,1,1,3,3-pentafluoropropane (HFC-245fa) in the vapor phase with a chromium-based catalyst at elevated temperature, or in the liquid phase with an alcoholic solution of KOH, NaOH, Ca(OH)₂ or Mg(OH)₂. In addition, methods for producing compounds in accordance with the present invention are described generally in connection with concurrently filed United States Patent Application entitled "Process for Producing Fluoropropenes" bearing attorney docket number (H0003789 (26267)).
The present compositions are believed to possess properties that are advantageous for a number of important reasons. For example, applicants believe, based at least in part on mathematical modeling, that the fluoroolefins of the present invention will not have a substantial negative affect on atmospheric chemistry, being negligible contributors to ozone depletion in comparison to some other halogenated species. The preferred compositions of the present invention thus have the advantage of not contributing substantially to ozone depletion. The preferred compositions also do not contribute substantially to global warming compared to many of the hydrofluoroalkanes presently in use.
Preferably, the compositions of the present invention have a Global Warming Potential (GWP) of not greater than 150, more preferably not greater than 100 and even more preferably not greater than 75. As used herein, "GWP" is measured relative to that of carbon dioxide and over a 140 year time horizon, as defined in "The Scientific Assessment of Ozone Depletion, 2002, a report of the World Meteorological Association's Global Ozone Research and Monitoring Project,".
The present compositions also preferably have an Ozone Depletion Potential (ODP) of not greater than 0.05, more preferably not greater than 0.02 and even more preferably about zero. As used herein, "ODP" is as defined in "The Scientific Assessment of Ozone Depletion, 2002, A report of the World Meteorological Association's Global Ozone Research and Monitoring Project".

STERILIZATION METHODS

Many articles, devices and materials, particularly for use in the medical field, must be sterilized prior to use for the health and safety reasons, such as the hearth and safety of patients and hospital staff. The present invention provides methods of sterilizing comprising contacting the articles, devices or material to be sterilized with a compound or composition of the present invention. Such methods may be either high or low-temperature sterilization methods. In certain embodiments, high-temperature sterilization comprises exposing the articles, device or material to be sterilized to a hot fluid comprising a compound or composition of the present invention at a temperature of from about 121°C (250°F) to about 132°C (270°F), preferably in a substantially sealed chamber. The process can be completed usually in less than about 2 hours. However, some articles, such as plastic articles and electrical components, cannot withstand such high temperatures and require tow temperature sterilization.
Low-temperature sterilization of the present invention involves the use of a compound or composition of the present invention at a temperature of from about 38 to about 93°C (100 to about 200°F). The compounds of the present invention may be combined with other common chemical sterilants, including, for example, ethylene oxide (EO), formaldehyde, hydrogen peroxide, chlorine dioxide, and ozone to form a sterilant composition of the present invention.
The low-temperature sterilization of the present Invention is preferably at least a two-step process performed in a substantially sealed, preferably air tight, chamber. In the first step (the sterilization step), the articles having been cleaned and wrapped in gas permeable bags are placed in the chamber. Air is then evacuated from the chamber by pulling a vacuum and perhaps by displacing the air with steam. In certain embodiments, it is preferable to inject steam into the chamber to achieve a relative humidity that ranges preferably from about 30% to about 70%. Such humidities may maximize the sterilizing effectiveness of the sterilant which is introduced into the chamber after the desired relative humidity is achieved. After a period of time sufficient for the sterilant to permeate the wrapping and reach the Interstices of the article, the sterilant and steam are evacuated from the chamber
In the preferred second step of the process (the aeration step), the articles are aerated to remove sterilant residues. Removing such residues is particularly important in the case of toxic sterilants, although it is optional in those cases in which the substantially non-toxic compounds of the present invention are used. Typical aeration processes include air washes, continuous aeration, and a combination of the two. An air wash is a batch process and usually comprises evacuating the chamber for a relatively short period, for example, 12 minutes, and then introducing air at atmospheric pressure or higher into the chamber. This cycle is repeated any number of times until the desired removal of sterilant is achieved. Continuous aeration typically involves introducing air through an inlet at one side of the chamber and then drawing it out through an outlet on the other side of the chamber by applying a slight vacuum to the outlet frequently, the two approaches are combined. For example, a common approach involves performing air washes and then an aeration cycle.

EXAMPLES

REFERENCE EXAMPLE 1

The coefficient of performance (COP) is a universally accepted measure of refrigerant performance, especially useful in representing the relative thermodynamic efficiency of a refrigerant in a specific heating or cooling cycle involving evaporation or condensation of the refrigerant. In refrigeration engineering, this term expresses the ratio of useful refrigeration to the energy applied by the compressor in compressing the vapor. The capacity of a refrigerant represents the amount of cooling or heating it provides and provides some measure of the capability of a compressor to pump quantities of heat for a given volumetric flow rate of refrigerant. In other words, given a specific compressor, a refrigerant with a higher capacity will deliver more cooling or heating power. One means for estimating COP of a refrigerant at specific operating conditions is from the thermodynamic properties of the refrigerant using standard refrigeration cycle analysis techniques (see for example, R.C. Downing, FLUOROCARBON REFRIGERANT HANDBOOK, Chapter 3, Prentice-Hall, 1988).

A refrigeration /air conditioning cycle system is provided where the condenser temperature is about 66°C (150°F) and the evaporator temperature is about -37°C (-35°F) under nominally isentropic compression with a compressor inlet temperature of about 10°C (50°F). COP is determined for several compositions of the present disclosure over a range of condenser and evaporator temperatures and reported in Table I below, based upon HFC-134a having a COP value of 1.00, a capacity value of 1.00 and a discharge temperature of 79°C (175 °F).

TABLE I

REFRIGERANT COMPOSTION	Relative COP	Relative CAPACITY	DISCHARGE TEMPERATURE °C (°F)
HFO 1225ye	1.02	0.76	70 (158)
HFO trans-1234ze	1.04	0.70	74 (165)
HFO cis-1234ze	1.13	0.36	68 (155)
HFO 1234yf	0.98	1.10	76 (168)

This example shows that certain of the preferred compounds for use with the present compositions each have a better energy efficiency than HFC-134a (1.02, 1.04 and 1.13 compared to 1.00) and the compressor using the present refrigerant compositions will produce discharge temperatures (70°C (158°F), 74°C (165°F) and 68°C (155°F) compared to 79°C (175°F)), which is advantageous since such result will likely leading to reduced maintenance problems.

REFERENCE EXAMPLE 2

The miscibility of HFO-1225ye and HFO-1234ze with various refrigeration lubricants is tested. The lubricants tested are mineral oil (C3), alkyl benzene (Zerol 150), ester oil (Mobil EAL 22 cc and Solest 120), polyalkylene glycol (PAG) oil (Goodwrench Refrigeration Oil for 134a systems), and a poly(alpha-olefin) oil (CP-6005-100). For each refrigerant/oil combination, three compositions are tested, namely 5, 20 and 50 weight percent of lubricant, with the balance of each being the compound of the present disclosure being tested
The lubricant compositions are placed in heavy-walled glass tubes. The tubes are evacuated, the refrigerant compound in accordance with the present disclosure is added, and the tubes are then sealed. The tubes are then put into an air bath environmental chamber, the temperature of which is varied from about-50°C to 70°C. At roughly 10°C intervals, visual observations of the tube contents are made for the existence of one or more liquid phases. In a case where more than one liquid phase is observed, the mixture is reported to be immiscible. In a case where there is only one liquid phase observed, the mixture is reported to be miscible. In those cases where two liquid phases were observed, but with one of the liquid phases occupying only a very small volume, the mixture is reported to be partially miscible.
The polyalkylene glycol and ester oil lubricants were judged to be miscible in all tested proportions over the entire temperature range, except that for the HFO-1225ye mixtures with polyalkylene glycol, the refrigerant mixture was found to be immiscible over the temperature range of -50°C to -30°C and to be partially miscible over from -20 to 50°C. At 50 weight percent concentration of the PAG in refrigerant and at 60°, the refrigerant/PAG mixture was miscible. At 70°C, it was miscible from 5 weight percent lubricant in refrigerant to 50 weight percent lubricant in refrigerant.

REFERENCE EXAMPLE 3

The compatibility of the refrigerant compounds and compositions of the present invention with PAG lubricating oils while in contact with metals used in refrigeration and air conditioning systems is tested at 350° C. representing conditions much more severe than are found in many refrigeration and air conditioning applications.
Aluminum, copper and steel coupons are added to heavy walled glass tubes. Two grams of oil are added to the tubes. The tubes are then evacuated and one gram of refrigerant is added. The tubes are put into an oven at 177°C (350°F) for one week and visual observations are made. At the end of the exposure period, the tubes are removed.
This procedure was done for the following combinations:

1. a) HFC-1234ze and GM Goodwrench PAG oil
2. b) HFC1243 zf and GM Goodwrench oil PAG oil
3. c) HFC-1234ze and MOPAR-56 PAG oil
4. d) HFC-1243 zf and MOPAR-66 PAG oil
5. e) HFC-1225 ye and MOPAR-56 PAG oil.

In all cases, there is minimal change in the appearance of the contents of the tube. This indicates that the refrigerant compounds and compositions of the present invention are stable in contact with aluminum, steel and copper found in refrigeration and air conditioning systems, and the types of lubricating oils that are likely to be included in such compositions or used with such compositions in these types of systems.

COMPARATIVE EXAMPLE

Aluminum, copper and steel coupons are added to a heavy walled glass tube with mineral oil and CFC-12 and heated for one week at 350°C, as in Reference Example 3. At the end of the exposure period, the tube is removed and visual observations are made. The liquid contents are observed to turn black indicating there is severe decomposition of the contents of the tube.
CFC-12 and mineral oil have heretofore been the combination of choice in many refrigerant systems and methods. Thus, the refrigerant compounds and compositions of the present disclosure possess significantly better stability with many commonly used lubricating oils than the widely-used prior art refrigerant-lubricating oil combination.

Claims

A method of sterilizing an article comprising contacting said article with a composition comprising a pentafluoropropene (HFO-1225).
A method according to claim 1, wherein the at least one pentafluoropropene (HFO-1225) comprises 1,2,3,3,3,-pentafluoropropene (HFO-1225ye).
A method according to claim 1 or claim 2, wherein said composition has a Global Warming Potential (GWP) of not greater than about 150.
A method according to any preceding claim, wherein said composition has an Ozone Depletion Potential of not greater than 0.05.
A method according to any preceding claim, wherein the method is a high temperature sterilization method, wherein the article to be sterilised is exposed to a hot fluid comprising at least one fluoroalkene as claimed in any preceding claim at a temperature of from 121°C (250°F) to 132°C (270°F).
A method according to claim 5, wherein the article to be sterilised is exposed to the hot fluid for less than two hours.
A method as claimed in any preceding claim, wherein the said article is contacted with a composition as claimed in any of claims 1 to 4 at a temperature of about 38°C to 93°C (100 to 200 °F).
A method according to claim 7, wherein the article is a plastic article or electrical component.
A method as claimed in claim 7 or claim 8, wherein the sterilisation step is carried out in a substantially sealed, preferably air tight chamber.
A method as claimed in claim 9, wherein the relative humidity of the chamber is from about 30% to about 70%.
A method as claimed in claim 9 or claim 10, wherein the article is aerated to remove the composition as claimed in claims 1 to 4.
A method as claimed in claim 11, wherein the aeration includes air washes, continuous aeration or a combination of the two.
A method as claimed in any preceding claim wherein the fluoroalkene is combined with ethylene oxide, formaldehyde, hydrogen peroxide, chlorine dioxide or ozone.
A sterilant composition as defined in any of claims 1 to 4, preferably wherein the composition further comprises a chemical sterilant selected from the group consisting of ethylene oxide, formaldehyde, hydrogen peroxide, chlorine dioxide or ozone.